Ob: Placenta Previa

Front 1

Define Placenta previa according to the latest SOGC guideline

Back 1

implanted in the lower segment of the uterus
presenting ahead of the leading pole of the fetus

Front 2

What is the incidence of placenta previa in:
1) singleton pregnancies
2) twin pregnancies

Back 2

1) 3/1000
2) 4/1000

Front 3

Is perinatal moratlity increased in pregnancies with placenta previa?

Back 3

yes

3-4X background normal

Front 4

Approximately what percentage of placental localizations will change when more accurate TVUS is used over transabdominal US?

Back 4

60%

Front 5

What are some reasons TVUS is more accurate than TAUS?

Back 5

can't see posterior placenta
fetal parts in the way
obesity
bladder under/over-filling

Front 6

For TVUS and detection of placenta previa, what is the
1) sensitivity
2) specificity

Back 6

1) 88%
2) 99%

Front 7

Placental overlap with the internal os of how much at 26 weeks gestation predicts the need for C/S at term?

Back 7

>2cm

if <2cm, most patients will not have previa at term

Front 8

Placenta previa with how much overlap at the 18-20 detailed anatomy scan is associated with increased risk for previa at term?

Back 8

>1.5cm

Front 9

Is there any evidence to support in verus out-patient management for placenta previa according to SOGC guidelines?

Back 9

No.

(outpt management may be appropriate for stable women)

Front 10

Is there evidence to recommend cervical cerclage in prolonging pregnancy in patients with previa?

Back 10

No

Front 11

What is the current incidence of placenta accreta (morbidly adherent placenta)?

Back 11

1/2500

Front 12

What is the risk of placenta accreta in women with a placenta previa and
1) one prior C/S
2) two prior C/S

Back 12

1) 25%
2) 40%